Percentage Decrease Calculator

Percentage Decrease in Excel

Excel and Google Sheets both love explicit numerators and denominators. Avoid hidden rounding in the headline cell.

Percentage Decrease Calculator

Quick answer

Use ((A1−B1)/A1) when A1 is baseline and B1 is new; format the result as a percent if you like.

((baseline cell − new cell) / baseline cell)

Introduction

After you trust a row in Excel, you can spot-check it with the Percentage Decrease Calculator.

If the algebra is rusty, read the percentage decrease formula once, then build the column formula below.

Main content

What is it?

Spreadsheets make it easy to repeat the same decrease calculation for many SKUs, weeks, or classrooms. The definition does not change; only the scale does.

A single wrong anchor (dragging the formula one row off) can mislabel an entire column; lock references or use a table so headers stay obvious.

Google Sheets follows the same pattern; export conventions differ slightly, but the ratio in the cell is identical.

Formula in sheets

=(A1-B1)/A1

Wrap with parentheses if you combine with other operations, and keep an eye on divide-by-zero when baseline cells can be empty.

Use IFERROR only after you understand what you are hiding from reviewers.

For narrative context on what the ratio means, pair this sheet with what is percentage decrease when you onboard teammates who only know “percent off” from retail.

Step-by-step

  1. Put baseline values in column A and new values in column B starting row 2.
  2. In C2 enter =(A2-B2)/A2 and fill down.
  3. Format column C as Percentage with the precision your style guide requires.
  4. Add a column for notes when baselines differ by row.
  5. Compare a few rows against the worked pairs in percentage decrease examples before you email the sheet.

Quick sample

A2=200, B2=150 → C2 shows 0.25 → 25% when formatted as percent.

Copy the formula down ten rows of SKUs; each row should still use its own A column cell as baseline, not a fixed $200.

If C2 shows #DIV/0!, the baseline cell is empty or zero; fix the source data instead of masking the error without a note.

FAQ

Should I multiply by 100 in the cell?
Not if you use percent number format; the spreadsheet displays 100× the decimal.
Pivots?
Aggregate first, then compute decrease on aggregated baselines if that matches your metric definition.
Array formulas vs fill down?
Either works; prefer clarity for reviewers. A filled column with explicit A and B references is easier to audit than a nested dynamic array for this simple ratio.

Conclusion

Summary

Excel shines at repeatability; narrative still needs the baseline in words.

Cross-check tricky rows on the home calculator when something looks off.

Save a version tab that documents which column is baseline so the next editor does not swap A and B.

Open the calculator

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